Book Image

Modern Python Cookbook - Second Edition

By : Steven F. Lott
Book Image

Modern Python Cookbook - Second Edition

By: Steven F. Lott

Overview of this book

Python is the preferred choice of developers, engineers, data scientists, and hobbyists everywhere. It is a great language that can power your applications and provide great speed, safety, and scalability. It can be used for simple scripting or sophisticated web applications. By exposing Python as a series of simple recipes, this book gives you insight into specific language features in a particular context. Having a tangible context helps make the language or a given standard library feature easier to understand. This book comes with 133 recipes on the latest version of Python 3.8. The recipes will benefit everyone, from beginners just starting out with Python to experts. You'll not only learn Python programming concepts but also how to build complex applications. The recipes will touch upon all necessary Python concepts related to data structures, object oriented programming, functional programming, and statistical programming. You will get acquainted with the nuances of Python syntax and how to effectively take advantage of it. By the end of this Python book, you will be equipped with knowledge of testing, web services, configuration, and application integration tips and tricks. You will be armed with the knowledge of how to create applications with flexible logging, powerful configuration, command-line options, automated unit tests, and good documentation.
Table of Contents (18 chapters)
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Replacing a file while preserving the previous version

We can leverage the power of pathlib to support a variety of filename manipulations. In the Using pathlib to work with filenames recipe, earlier in this chapter, we looked at a few of the most common techniques for managing directories, filenames, and file suffixes.

One common file processing requirement is to create output files in a fail-safe manner. That is, the application should preserve any previous output file, no matter how or where the application fails.

Consider the following scenario:

  1. At time t0, there's a valid output.csv file from the previous run of the application.
  2. At time t1, we start running the application. It begins overwriting the output.csv file. Until the program finishes, the bytes are unusable.
  3. At time t2, the application crashes. The partial output.csv file is useless. Worse, the valid file from time t0 is not available either since it...